Guys, a couple of things - I've never used flux core, bought a MIG so I could get AWAY from a bunch of cleanup - I have seen others just take the nozzle OFF the gun for flux core, but the factory adapter keeps the threads, etc, from getting messed up.
Helmets - most of 'em let light in, but the auto darks are so much less of a PITA for changing shade it's usually worth the irritation. I keep meaning to take some thin leather and build both a "beard" and a hat to rivet onto at least one of mine, just haven't got to it yet.
MIG is definitely a different animal than stick for visibility; the only angle I've found that works is to be alongside the weld path, not behind it - from there you can tell if your stickout is right, if your slight rearward tilt of the wire is right, etc - it DOES make it a bit harder to keep the bead STRAIGHT, but not impossible. If you want even MORE "fun", try a full size spool gun 10 feet in the air with a 6-7 mph wind -

the plywood in the background was clamped to the .120 wall 2" tubing to block some wind; I also upped the gas to around 25 scfh instead of the usual 18-20. Can't really blame the vertical on wind, I just suck at vertical up... These others (all untouched after weld) were inside with normal mig gun, MM252/.035 Lincoln L56 wire/C25 gas -
This is the roof frame where they eventually ended up -
I'm now on my second and third MIG, bought the first one (now belongs to a friend) at least 10 years ago and since then I've used stick maybe TWICE - everything else gets done with the same combo mentioned above, from welding 14 ga. fence wire to emt conduit, up to 3/4" flat bar for 20 ton bending jigs. Best advice I ever got was from Jody at weldingtipsandtricks.com - specifically, to stay at the front of the puddle (in direction of travel), and NOT assume you're getting penetration unless you SEE the arc touch the parent metal.
HTH... Steve